Displacement devices typically comprise moveable stages which move relative to a stator and/or relative to an environment in which they are located. Displacement devices are widely used in various manufacturing, inspection, sample/part transfer, and assembly processes. A common solution currently in use achieves XY (i.e. planar) motion of the moveable stage using a toothed belt/chain transfer system. Another common solution currently in uses achieves XY motion of the moveable stage by stacking two linearly moveable stages (i.e. an X-stage and a Y-stage) together via connecting bearings.
Some generally more desirable solutions involve having one or more moveable stages capable of XY (i.e. planar) motion and, where a displacement device comprises more than one moveable stage, allowing more than one of such moveable stages to share a common working region and/or a common stator. It might be desirable for such a moveable stage to be able to provide two-dimensional programmable motion. Attempts have been made to design such displacement devices using the interaction between current-carrying coils and permanent magnets. Examples of efforts in this regard include the following: U.S. Pat. No. 6,003,230; U.S. Pat. No. 6,097,114; U.S. Pat. No. 6,208,045; U.S. Pat. No. 6,441,514; U.S. Pat. No. 6,847,134; U.S. Pat. No. 6,987,335; U.S. Pat. No. 7,436,135; U.S. Pat. No. 7,948,122; U.S. Pat. No. 8,593,016; U.S. Pat. No. 8,686,602; US patent publication No. 2008/0203828; W. J. Kim and D. L. Trumper, High-precision magnetic levitation stage for photolithography. Precision Eng. 22 2 (1998), pp. 66-77; D. L. Trumper, et al, “Magnet arrays for synchronous machines”, IEEE Industry Applications Society Annual Meeting, vol. 1, pp. 9-18, 1993; and J. W. Jansen, C. M. M. van Lierop, E. A. Lomonova, A. J. A. Vandenput, “Magnetically Levitated Planar Actuator with Moving Magnets”, IEEE Tran. Ind. App., Vol 44, No 4, 2008.
There is a general desire to provide displacement devices having characteristics that improve upon those known in the prior art.
The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.